> How might we make books actually work reliably?

The read is interesting, and it has an interesting premise. But, it is one well known.

Techniques like SQ3R (https://en.wikipedia.org/wiki/SQ3R) have existed for decades.

Books are a great source of knowledge. But, you need to use the right techniques to read them.

If you read for fun, then don't bother. Whatever sticks is better than nothing.

If you read to memorize, use memory techniques.

If you read to understand (like math), do exercises. All the reading in the world is not going to make you a math expert without tyring it for yourself.